* [PATCH] nohz: Fix local_timer_softirq_pending()
@ 2018-07-31 16:13 Anna-Maria Gleixner
2018-07-31 16:50 ` Paul E. McKenney
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: Anna-Maria Gleixner @ 2018-07-31 16:13 UTC (permalink / raw)
To: linux-kernel
Cc: bigeasy, tglx, frederic, bristot, paulmck, peterz, Anna-Maria Gleixner
local_timer_softirq_pending() checks whether the timer softirq is
pending with: local_softirq_pending() & TIMER_SOFTIRQ.
This is wrong because TIMER_SOFTIRQ is the softirq number and not a
bitmask. So the test checks for the wrong bit.
Use BIT(TIMER_SOFTIRQ) instead.
Fixes: 5d62c183f9e9 ("nohz: Prevent a timer interrupt storm in tick_nohz_stop_sched_tick()")
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
kernel/time/tick-sched.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index da9455a6b42b..5b33e2f5c0ed 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -642,7 +642,7 @@ static void tick_nohz_restart(struct tick_sched *ts, ktime_t now)
static inline bool local_timer_softirq_pending(void)
{
- return local_softirq_pending() & TIMER_SOFTIRQ;
+ return local_softirq_pending() & BIT(TIMER_SOFTIRQ);
}
static ktime_t tick_nohz_next_event(struct tick_sched *ts, int cpu)
--
2.18.0
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] nohz: Fix local_timer_softirq_pending()
2018-07-31 16:13 [PATCH] nohz: Fix local_timer_softirq_pending() Anna-Maria Gleixner
@ 2018-07-31 16:50 ` Paul E. McKenney
2018-07-31 17:07 ` Daniel Bristot de Oliveira
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Paul E. McKenney @ 2018-07-31 16:50 UTC (permalink / raw)
To: Anna-Maria Gleixner
Cc: linux-kernel, bigeasy, tglx, frederic, bristot, peterz
On Tue, Jul 31, 2018 at 06:13:58PM +0200, Anna-Maria Gleixner wrote:
> local_timer_softirq_pending() checks whether the timer softirq is
> pending with: local_softirq_pending() & TIMER_SOFTIRQ.
>
> This is wrong because TIMER_SOFTIRQ is the softirq number and not a
> bitmask. So the test checks for the wrong bit.
>
> Use BIT(TIMER_SOFTIRQ) instead.
>
> Fixes: 5d62c183f9e9 ("nohz: Prevent a timer interrupt storm in tick_nohz_stop_sched_tick()")
> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2729 opportunities to change "1UL << x" to "BIT(x)", including
__raise_softirq_irqoff(). I did the two in RCU. ;-)
Thanx, Paul
> ---
> kernel/time/tick-sched.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> index da9455a6b42b..5b33e2f5c0ed 100644
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -642,7 +642,7 @@ static void tick_nohz_restart(struct tick_sched *ts, ktime_t now)
>
> static inline bool local_timer_softirq_pending(void)
> {
> - return local_softirq_pending() & TIMER_SOFTIRQ;
> + return local_softirq_pending() & BIT(TIMER_SOFTIRQ);
> }
>
> static ktime_t tick_nohz_next_event(struct tick_sched *ts, int cpu)
> --
> 2.18.0
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] nohz: Fix local_timer_softirq_pending()
2018-07-31 16:13 [PATCH] nohz: Fix local_timer_softirq_pending() Anna-Maria Gleixner
2018-07-31 16:50 ` Paul E. McKenney
@ 2018-07-31 17:07 ` Daniel Bristot de Oliveira
2018-07-31 17:14 ` Frederic Weisbecker
2018-07-31 20:13 ` [tip:timers/urgent] " tip-bot for Anna-Maria Gleixner
3 siblings, 0 replies; 5+ messages in thread
From: Daniel Bristot de Oliveira @ 2018-07-31 17:07 UTC (permalink / raw)
To: Anna-Maria Gleixner, linux-kernel
Cc: bigeasy, tglx, frederic, paulmck, peterz
On 07/31/2018 06:13 PM, Anna-Maria Gleixner wrote:
> local_timer_softirq_pending() checks whether the timer softirq is
> pending with: local_softirq_pending() & TIMER_SOFTIRQ.
>
> This is wrong because TIMER_SOFTIRQ is the softirq number and not a
> bitmask. So the test checks for the wrong bit.
>
> Use BIT(TIMER_SOFTIRQ) instead.
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Thanks!
-- Daniel
> Fixes: 5d62c183f9e9 ("nohz: Prevent a timer interrupt storm in tick_nohz_stop_sched_tick()")
> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
> ---
> kernel/time/tick-sched.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> index da9455a6b42b..5b33e2f5c0ed 100644
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -642,7 +642,7 @@ static void tick_nohz_restart(struct tick_sched *ts, ktime_t now)
>
> static inline bool local_timer_softirq_pending(void)
> {
> - return local_softirq_pending() & TIMER_SOFTIRQ;
> + return local_softirq_pending() & BIT(TIMER_SOFTIRQ);
> }
>
> static ktime_t tick_nohz_next_event(struct tick_sched *ts, int cpu)
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] nohz: Fix local_timer_softirq_pending()
2018-07-31 16:13 [PATCH] nohz: Fix local_timer_softirq_pending() Anna-Maria Gleixner
2018-07-31 16:50 ` Paul E. McKenney
2018-07-31 17:07 ` Daniel Bristot de Oliveira
@ 2018-07-31 17:14 ` Frederic Weisbecker
2018-07-31 20:13 ` [tip:timers/urgent] " tip-bot for Anna-Maria Gleixner
3 siblings, 0 replies; 5+ messages in thread
From: Frederic Weisbecker @ 2018-07-31 17:14 UTC (permalink / raw)
To: Anna-Maria Gleixner; +Cc: linux-kernel, bigeasy, tglx, bristot, paulmck, peterz
On Tue, Jul 31, 2018 at 06:13:58PM +0200, Anna-Maria Gleixner wrote:
> local_timer_softirq_pending() checks whether the timer softirq is
> pending with: local_softirq_pending() & TIMER_SOFTIRQ.
>
> This is wrong because TIMER_SOFTIRQ is the softirq number and not a
> bitmask. So the test checks for the wrong bit.
>
> Use BIT(TIMER_SOFTIRQ) instead.
>
> Fixes: 5d62c183f9e9 ("nohz: Prevent a timer interrupt storm in tick_nohz_stop_sched_tick()")
> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Thanks!
^ permalink raw reply [flat|nested] 5+ messages in thread
* [tip:timers/urgent] nohz: Fix local_timer_softirq_pending()
2018-07-31 16:13 [PATCH] nohz: Fix local_timer_softirq_pending() Anna-Maria Gleixner
` (2 preceding siblings ...)
2018-07-31 17:14 ` Frederic Weisbecker
@ 2018-07-31 20:13 ` tip-bot for Anna-Maria Gleixner
3 siblings, 0 replies; 5+ messages in thread
From: tip-bot for Anna-Maria Gleixner @ 2018-07-31 20:13 UTC (permalink / raw)
To: linux-tip-commits
Cc: tglx, linux-kernel, anna-maria, hpa, paulmck, frederic, mingo, bristot
Commit-ID: 80d20d35af1edd632a5e7a3b9c0ab7ceff92769e
Gitweb: https://git.kernel.org/tip/80d20d35af1edd632a5e7a3b9c0ab7ceff92769e
Author: Anna-Maria Gleixner <anna-maria@linutronix.de>
AuthorDate: Tue, 31 Jul 2018 18:13:58 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 31 Jul 2018 22:08:44 +0200
nohz: Fix local_timer_softirq_pending()
local_timer_softirq_pending() checks whether the timer softirq is
pending with: local_softirq_pending() & TIMER_SOFTIRQ.
This is wrong because TIMER_SOFTIRQ is the softirq number and not a
bitmask. So the test checks for the wrong bit.
Use BIT(TIMER_SOFTIRQ) instead.
Fixes: 5d62c183f9e9 ("nohz: Prevent a timer interrupt storm in tick_nohz_stop_sched_tick()")
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Cc: bigeasy@linutronix.de
Cc: peterz@infradead.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180731161358.29472-1-anna-maria@linutronix.de
---
kernel/time/tick-sched.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index da9455a6b42b..5b33e2f5c0ed 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -642,7 +642,7 @@ static void tick_nohz_restart(struct tick_sched *ts, ktime_t now)
static inline bool local_timer_softirq_pending(void)
{
- return local_softirq_pending() & TIMER_SOFTIRQ;
+ return local_softirq_pending() & BIT(TIMER_SOFTIRQ);
}
static ktime_t tick_nohz_next_event(struct tick_sched *ts, int cpu)
^ permalink raw reply related [flat|nested] 5+ messages in thread
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2018-07-31 16:13 [PATCH] nohz: Fix local_timer_softirq_pending() Anna-Maria Gleixner
2018-07-31 16:50 ` Paul E. McKenney
2018-07-31 17:07 ` Daniel Bristot de Oliveira
2018-07-31 17:14 ` Frederic Weisbecker
2018-07-31 20:13 ` [tip:timers/urgent] " tip-bot for Anna-Maria Gleixner
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